1. Technical Field
The present invention relates to light-emitting devices, display apparatuses, and electronic systems.
2. Related Art
An organic electroluminescent (EL) device is a light-emitting device including at least one organic light-emitting layer between an anode and a cathode. In this type of light-emitting device, an electric field is applied between the anode and the cathode to inject electrons from the cathode into the light-emitting layer and holes from the anode into the light-emitting layer. The electrons and the holes then recombine together in the light-emitting layer to generate excitons. When the excitons return to the ground state, their energy is released in the form of light.
One such light-emitting device includes two light-emitting layers, corresponding to red (R) and blue (B), that are stacked between the anode and the cathode so that the device can emit white light (for example, see JP-A-2007-287691 (Patent Document 1)). This white light-emitting device can be used in combination with red (R) and blue (B) color filters provided in individual pixels to display a full-color image.
The light-emitting device according to Patent Document 1 further includes an intermediate layer between the light-emitting layers to limit migration of carriers (electrons and holes) between the light-emitting layers, thereby controlling the numbers of electrons and holes recombining together in the individual light-emitting layers. This improves the characteristics of the light-emitting device, including emission efficiency and emission lifetime.
The light-emitting device according to Patent Document 1, however, has insufficient emission efficiency because the intermediate layer is simply formed of a common hole-transporting or electron-transporting material.